Can't get correct value with QSettings and custom type-CodePudding

I am trying to read a small struct from my ini file using QSettings. Writing works fine, but when I try to read it back I always get the default value out of QVariant.

This is the structure definition:

struct CellSize {
    int font;
    int cell;
};

inline QDataStream& operator<<(QDataStream& out, const CharTableView::CellSize& v) {
    out << v.font << v.cell;
    return out;
}

inline QDataStream& operator>>(QDataStream& in, CharTableView::CellSize& v) {
    int font, cell;
    in >> font >> cell;
    v.font = font;
    v.cell = cell;
    return in;
}

inline bool operator==(const CharTableView::CellSize& a, const CharTableView::CellSize& b) {
    return a.font == b.font && a.cell == b.cell;
}

Q_DECLARE_METATYPE(CharTableView::CellSize)

I am writing with m_settings.setValue(Settings::TableCellSize, QVariant::fromValue<CharTableView::CellSize>(CharTableView::CellSizeSmall));. I assume this is working fine because the gibberish inside the ini file is consistent with the UI changes. My reading code is CharTableView::CellSize tableCellSize = m_settings.value(Settings::TableCellSize).value<CharTableView::CellSize>(); and it always gives me {0, 0}.

I'm fairly new to Qt and, to be honest, I am a litte confused by QVariant and all the metaprogramming stuff. Am I missing something?

EDIT: I have tried to set some breakpoints. Basically, the first breakpoint that gets triggered is the one after I've read the value from QSettings, which is {0, 0} as always. Then after a while a breakpoint inside operator>> gets triggered and the values of font and cell inside the operator function are correct. What's happening?

CodePudding user response：

I solved the issue! I had to add qRegisterMetaType<CharTableView::CellSize>() inside CharTableView constructor.